These clear designer stamps are made of high quality photopolymer. They have a microscopically porous surface which gives superior ink transfer with all types of ink! Ready to use with any clear acrylic block (sold separately).MEASUREMENT REFERENCE: This set comes on a 6x4 acetate sheet. The Fushia Floral image in top left is apx 3" wide and 3 tall. The humming bird in the left is apx 2 wide and 1.8 tall.